Hydraulic jack



jan. 17, 192s. y J. G. DYBENS HYDRAULIC `JACK Filed March 1e. 192e .67 65 y 69 70 65 if? 4% l 45 ATI'OR Patented Jan. 17, 1928. y

UNITED STATES JOHN e. iiYBiiNs, or Los PATENT OFFICE.

ANGELES, CALIFORNIA, ASSIGNOR T0 HERMAN' D. EBEBLE,

0F LOS ANGELES, CALIFORNIA.

HYDRAULIC JACK.

Application led March 16 opened in order to allow the liquid lto fiow from the piston chamber intof' the reservoir chamber when it is desired to lower the piston.

It is an object' of this invention to provide an hydraulic jack in which the passages; connecting the reservoir chamber and the piston chamber with the pump and the bypass passage are all connected together and designed for simplicity and economy in making and assembling these parts of the jaclng 'It is another object of this invention to provide an hydraulic jack in which the cylinders forming the piston chamber and the reservoir chamber are assembled together in an improved and simplified manner.

In the ordinary hydraulic ack, when oil is drawn from the reservoir chamber and forced into the piston chamber, a vacuum is created in the reservoir chamber which, of course, tends to revent the liquid from being drawn there rom.

It is an object of this invention to provide a-vacuum relief valve whereby air may be introducedinto the reservoir chamber when the oil is drawn therefrom so that there will be no vacuum created.

It is another object of this invention to provide a vacuum valve of the character.

mentioned which, is closed when the piston is in lower osition so that there will be no leakage o oil therethrough from the reservoir chamber. l

Referring to the drawing in which I illustrate a preferred form of my invention,

Fig. 1 is a perspective view of a jack embodying the features of this invention. y

Fig. 2 is a vertical cross section taken subltantlally as indicated by the line 2 2 of i 1. Fig.4 3 is a fragmentary section taken as indicated by the line 3-"3 of Fig. 1.

', 1926. Serial No. 93,041.

Fig. 4 is an enlarged fra mentary detail of the vacuum relief valve o this invention. Referring particularly' to Figs. 1 and 2 of the drawing, my inventionl rovides a base 11 having a central threade cavit 12 into which the lower end of an inner cy inder 13 is Secured, this inner'cylinder 13 providing a piston chamber 14. The upper end of the inner cylinder 13 is screwed into a threaded cavity 15.0f a cap 16. A piston 17 is placed in the piston chamber 14 and is adapted to move from a lower into an upper position.

Extending from the piston 17 is a stem 18 which projects through a stuiiing box 19 of the cap 16, there being a head 21 Aformed at the upper end of the stem 18..

Surrounding the threaded cavity 12 of the base 11 is an annular internal beveled seat 2 3/and surrounding the threaded cavity 15 of 'the cap 16 `is an annular external beveled seat 24. The numeral 25 represents an outer cylinder which surrounds the inner cylinder 13 and forms an annular reservoir chamber 26; 28 represents an u per internal beveled end of the outer cylin er 25 and 29 represents a lower external beveled end of the outer cylinder 25. The beveled ends 28 and`29 are forcibly engaged respectively bythe beveled seats 24 and 23 of the cap 16 for the base 11. In assembling these parts, the inner cylinder 13 may first be screwed into the threaded cavity 12 of the base 11g The outer cylinder 25 may then be setin position to surround the inner cylinder 13, whereafter the cap 16 is screwed onto the upper end of the inner cylinder 13, the upper threaded end of the cylinder 13 advancing into the threaded cavity 15 of the cap 16. The cap 16 is screwed onto the inner cylinder 13 to such an extent that the beveled faces 23 and 24 forcibly engage the beveled ends 29 and 28 of the outer cylinder 25 a sufficient amount to form tight joints between the parts 11, 16 and 25. This construction is very simple and lisvery easy to assemble. l l

The body 11 has a projection 30 which extends upwardly at one side of -the outer cylinder 25, this projection 30lproviding a pump cylinder 31 in which a glimp) plunger 32 is placed, there being a stul g ox 33 at the upper end of the cylinder. 31 to form a seal thereat. The'upper end of the plunger 32 may be provided in the form .of a clevis 35 which is attached to an operating arm 37 by a pin 36. The operating arm 37 is also attached to a link 38, as illustrated in Fig. l, the lower end of-this link being pivoted to the base.

The reservoir chamber 26 is connected to the lower 'end of the pump cylinder 31 by means of a suction passage 42. The suction passage 42 is enlarged at its outer end at 43 so as to provide a seat 44. Adapted to engage the seat 44 is an intake valve in the form of a ball 45. The ball 45 is held in the left end of the enlarged part 43 by means of a pin 46 which extends from a plug 47 which is thi'eadedly secured in the right end of the enlarged part 43. A branch 49 of the suction passage 42l connects between the enlarged part 43 and the lower end of the pump cylinder 3l. The lower end ofthe piston chamber 14 is connected to the lower end of the pump cylinder 31 by means of an exhaust passage 5l. The exhaust passage 51 is drilled from the right end of the base l11 and is enlarged at 52 so as to-provide a seat 53. Extended into the enlarged part 52 is an exhaust valve unit 54 having a body 55. The outer part of the body 55 is threaded at 56 and screws into the enlarged part 52 so that the left end of the body engages the seat 53 and there is a tight seal provided thereat. The left end of the body 55 has a chamber 57 in which a ball valve 58 is placed. ,The ball valve is adaptedto en age a seat 59 and to close an opening 60 w ich is communicated with the lower end of the pump cylinder 31 by means' of a diametrical opening 62. A by-pass opening 64 is drilled so as to connect the suction passage 42 and the exhaust passage 51 together at a point between the reservoir chamber and the piston chamber and the pump cylinder 31. The by-pass passage is-enlarged at 65 so as to provide a seat 66. Extending into the enlarged part 65 of the by-pass passage 64 is a by-pass valve 67. The upper end of the by-pass valve 67 is surrounded by a stuffing box 68. A gland 69- of the stuffing box is provided with internal threads and the valve 67 is provided with external threads 70 which screw into the internal threads of the gland 69 so thatrthe by-pass valve 67 may be advanced in either direction. The lower part 72 of the by-pass valve 67 is of smaller size than the enlarged part 65 of the by-pass passage 64. Therefore, the extending of the lowe'r end 72 into the portion 65 does not obstruct a iow of oil through the suction passage 42, since there is a space left thereraised by operating'the pump plunger 32,-

around through which the oil may iow into the enlarged part 43 of the suction passage 42.

Considering the piston 17 to be in lower position in the piston chamber 14, it may be `this being done by oscillatin the member 37. vDuring the up stroke o the. plunger 32, the ball valve 58 in the chamber 57 is pulled against its seat and prevents a ilow from the piston chamber 14 into the lower end of the pump cylinder 31. The suction valve 45, however, is withdrawn from its seat against the end of the pin 46 and liquid is drawn from the reservoir chamber 26 into the pump cylinder 31 through the Suction passage 42, it being understood that the reservoirchamber 26 is filled with a liquid which is of aviscous nature such as heavy lubricating oil. During the down stroke of the plunger 32, the suction valve 45 is forced against the seat 44 and the suction passage 42 is closed so that there cannot be a flow of oil from the pump cylinder 31 to the reservoir chamber 26. The ball 58, however, is forced fiom its seat 59 and the oil previously drawn into the pump cylinder 31 is forced through the exhaust passage 51 into the lower end of the piston chamber 14. As oil is forced into the piston chamber 14 the piston 17 is moved upwardly from a lowered position into a raised position, as shown in Figs. 1 and 2. When it is desired to lower the piston 17 and to lower the jack, the oil in the piston chamber must be returned to the reservoir chamber. This is accomplished by unscrewing the by-pass valve 67 so that it disengages from the seat 66. This opens the by-pass passage 64 and oil may flow from the piston chamber 14 through a part of the exhaustl passage 51, the by-pass passage 64 and through a part of the suction passage 42 into the reservoir chamber 26.

From an inspection of Fig. 2, it will be obvious that as the oil is withdrawn from the reservoir chamber 26a vacuum will be created thereab'ove and this vacuum `,vill tend to resist the withdrawal of the oil from this reservoir chamber. My invention provides a vacuum relief valve 70 which is shown best in Figs. 2 and 4. The cap 16 is provided with an opening 71 which extends from the 'exterior to the interior of the reservoir chamber 26. A body 72 of the vacuum relief valve 70 extends through the opening 71 and has a threaded portion 73 which screws into a threaded portion of the opening 71, whereby it is secured in place. The

body 72 is rovided with a cavity 74 which is decreased) in size at 76 so as to provide an annular seat as indicated at 77. The lower end of the cavity 74 is connected to the upper part of the reservoir chamber 26 by means of a small opening .78. A valve 79 is placed in the cavity 74 in position to engage the seat 77. Placed below a projection 81 of the valve 79, which projection extends into the small part 76 of the cavity 74, is a spring 82A which tends to keep it elevated and-unseat, the valve 79. In the upper part of the cavity 74 is a valve urger 83 having a stem 84, which projects through a swedged portion 85 at the upper part of the cavity 7 4, and has a head-85 which rests invention the inside the upper part of the cavity 74. Situatedbetween the head 85a and the valve 79 is a spring 86. Channels 88 extend from the upper end of the cavity 74 to a point adjacent to the seat 77, and channels 89 extend from the seat 77 to thc lower part of the small part 76 of the cavity 74. The vacuum relief valve is situated in such a position that the stem 84 of the urger 83 rests below the head 21. When the head 21 moves into lower position, as indicated by dotted lines 90 in Fig. 1, the stem 84 is enraged and the urger 83 is pressed downward- Ty into the position shown in Fig. 4. A pressure is transferred through the spring 86 against the valve 79, the valve 79 being forced against the seat 77 so that the cavity 7 4 is closed. The spring 82 below the valve 79 is of suhcient strength to keep it unseated at all times except when the head 2l is in engagement with the stem 84 of the urger 83. From this it will be seen that when the piston 17 is in lowered position and the jack is not in use, the valve 79 will be in engagement with the seat 77 and the =passage through the body 7 2 will be closed.

When the jack is operated and oil is withdrawn from the reservoir chamber 26, the',

head 21 will be `moved from engagement with the urger 83 and the spring 82 will lift the valve 79 from its seat. This opens the passage through the body 72 and communicates the reservoir chamber 26 with the atmosphere. Therefore, whenever oil is being withdrawn from the reservoir chamber 26,

air may enter thereinto relief valve 70. Also, turned to the reservoir viously drawn thereinto through the vacuum relief valve 70 may be exhausted therethrough. This valve arrangement 'of my eliminates any vacuum in the reservoir chamber 26 at any time but is so designed that the valve will be closed when jack is not in use so that there. cannot be any leakage in -event that the jack was laid on its side so that oil would run out if the valve closing means were' not provided.

From the foregoing description it will be evident that this Jinvention provides a jack having three main features: first, the novel construction of passages connecting the reservoir chamber and the piston chamber with the pump cylinder 31, the valve constructions. and the by-pass construction; second, the novel means whereby the inner and outer cylinders 13 and 25 are secured in place which is very satisfactory because they are economical to produce and economical to assemble; and, third, the vacuum relief valve 70 which prevents thecreating of a vacuum in therescrvoir chamber 26, but also prevents a leakage of oil from the chamber when the jack is not in use.

through the vacuum whenoil is being rechamber 26 air pre-I I claim as my invention:

l. An hydraulic jack comprising: a base having a threaded portion and an annular beveled seat surrounding said threaded portion; an inner cylinder having the lower endl screwed to. said threaded portion of said base; a cap having a -threaded portion to which the upper end 0f said inner cylinder is screwed, and an annular beveled seat surrounding said threaded portion; and an outer cylinder having-the ends thereof beveled, said beveled 'ends bein Iforcibly engaged by said annular bevele seats of said base and said cap, thus forming tight 'oints at the opposite ends of said outer cylin er.

2..An hydraulic jack comprising: walls forming a piston chamber and a reservoir chamber; a piston adapted to operate in said piston chamber; means for pumping a liquid from said reservoir chamber into said piston chamber and for allowin said liquid to return to said reservoir chamber from said piston chamber; a vacuum relief valve for admit-ting air into said reservoir chamber when liquid is taken therefrom and emitting air when said liquid is returned to said reservoir chamber; and means carried by said piston for closing said vacuum valve when said piston is approximately in lower position.

3. An hydraulic jack. comprising: walls forming a piston chamber and a reservoir chamber; a piston adaptedto operate in said piston chamber; means for pumping a liquid 'from said 'reservoir chamber into said piston piston chamber; a base attache to said walls forming said piston and reservoir chambers, said base having a pump cylinder, an exhaust passage connected to said piston chamber and said pump cylinder, a suction passage connected to said reservoir chamber and said pump cylinder, and a by-pass connected to said exhaust and said suction passages between said piston and said reservoir chambers and said pump cylinder; a suction valve in said suction passage for preventing a flow of liquid from said pump cylinder to` said reservoir chamber; an exhaust valve in said exhaust passage for preventin a How of liquid .from said pis'ton cham er to said pump cylinder; a pump plunger operable in said pump cylinder for drawing liquid from said reservoir chamber through sald suction passage and deliverin said li uid to said piston chamber throng said ex aust valve; a by-pass valve for closing said by-pass, said by-pass valve being manually Operable to permit said liquid to return through said exhaust passage, said by-pass and said suction passage from said piston chamber to said reservoir chamber; a vacuum relief valve for admitting air into said reservoir 10 chamber when liquid is taken therefrom and emitting air when said liquid is returned to said reservoir chamber; and means carried by said piston for closing said vacuum valve when said piston is approximately in lower position.

In testimony Whereof,-I have hereunto set my hand at Los Angeles, California, this 11th day of March, 1926.

JOHN G. DYBENS. 

